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Old Jan 13, 2007, 4:40 PM   #1
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My third party teleconverter came today. I was disappointed with the auto focusing hunting quite a bit. I read the manual and it said the 2x works best with lens aperture 3.5 and larger. Mine is 4.0 thru out. Should I try the 1.4? Is it worth it or just save up for a longer lens in the future. Thanks, donna
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Old Jan 13, 2007, 5:32 PM   #2
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hi Donna... remember, your 2x converter costsyou 2 stops, so your f4 lens turns into an f6.3. the 30D AF doesn't work at all unless the lens can open up to at least f6.3. evenat that aperture, AF will bespotty, and probably will hunt a bit, unless you have VERY good light. you could try a 1.4x convrter, that will only cost you 1 stop, so your lens will be f5.6 and the AFshould work better, but you won't have quite as much reach. a style="BACKGROUND-COLOR: #000000"lso, remember that converters cost you some a bit in terms of contrast and clarity as well, and with the 2x's the penalty is greater, which makes it harder to focus anyway. that's why i got a 1.4. that and the fact that my Sigma is f5.6 at the long end, and i could only give up one stop without losing AF entirely... :G
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Old Jan 13, 2007, 8:24 PM   #3
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Well, I am done with converters for now. I will lure the birds closer or shot landscapes...until I came buy a longer lens. But not anytime soon. I have good equipment and appreciate what I already own. I haven't scratched the surface of my current set-up. Donna
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Old Jan 14, 2007, 2:19 PM   #4
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Hi Donna. From what I've read about tc's, is that you multiply the magnification factor of the tc (2X's in your case), by the aperture of the lens you're using - so 2 x f/4 would be an f/8. As you know, this isn't very fast, and to af properly would more than likely need to be used in very good light. A 1.4tc would give you on your lens, a f/5.6, and you'd have around 300mm of length. Not too great either, but definitely better numbers than the tcX2. Hope this helps a little........Don.
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Old Jan 14, 2007, 6:03 PM   #5
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Thanks I will stick with what I have for now. donna
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